On Friday, October 11, 2019 3:30:41 PM CEST Yin, Fengwei wrote: > > On 10/11/2019 5:05 PM, Rafael J. Wysocki wrote: > > Sorry for the delay. > No problem. > > > > > On Monday, September 9, 2019 9:39:37 AM CEST Yin Fengwei wrote: > >> In function acpi_idle_do_entry(), we do an io port access to guarantee > >> hardware behavior. But it could trigger unnecessary vmexit for > >> virtualization environemnt. > > > > Is this a theoretical problem, or do you actually see it? > > > > If you see it, I'd like to have a pointer to a bug report regarding it > > or similar. > We did see this issue when we run linux as guest with ACRN hypervisor > instead of kvm or xen. In our case, we export all native C states to > guest and let guest choose which C state it will enter. > > And we observed many pm timer port access when guest tried to enter > deeper C state (Yes, we emulate pm timer so pm timer access will trigger > vmexit). Can you please put this information into the changelog of your patch? It works very well as a rationale for me. :-)
